Re: Savanna fantasies

On Oct 4, 6:14 am, Marc Verhaegen <m_verhae...@xxxxxxxxx> wrote:
...

A Diversity of ŒOpen Plains¹ Ideas

The original Œopen plain¹ ideas were obviously hypothetical, but soon the
general impression of human ancestors coming out of the trees and colonizing
the vast plains became set in the minds of most anthropologists, and
different ideas ­ some more improbable than others ­ were put forward to
explain how savannah-dwelling ancestors might have found enough food and
water to survive on the open plains ­ as if the hypothesis had already been
proven. Human characteristics were discussed in an evolutionary setting that
involved a movement from the forests to the open plains, and reasons for
these characteristics always tended to revolve around the Œopen plain¹ theme
(see Table 2). Even the most far-fetched of these ideas (for example, honey
collection, liver consumption, or food collection at noon on open plains)
have been seriously considered and published in scientific journals. Such ad
hoc explanations are comparable to the hypothetical Œland bridges¹ between
Africa and South-America that were popular in geology before the theory of
Plate Tectonics became accepted.
What is striking about these hypotheses is their combined diversity. Some
rely on hunting large game, others on small game, some on scavenging bone
marrow, or brains, or livers, or collecting seeds, or tubers, or honey. Some
of these Œopen plain¹ models are more typical of slow-moving animals
(feeding on belowground resources), others of fast-moving mammals (³bouts of
strenuous activity²), and others rely on endurance (following migrating
ungulates, or the dogged pursuit of prey). This diversity of theoretical
models suggests that the Œopen plain¹ scenarios are not the result of usual
biological thinking. In evolutionary biology, hypotheses are not just
Œpossible scenarios¹, but normally the result of solid analyses of
relationships between form and function. Biologists usually do not propose a
scenario to explain the evolution of an animal without a careful comparison
of different features of this animal with similar features (convergences) of
other, not closely related species.

Table 2. Diverse savannah hypotheses of human origins.

Raymond Dart 1960 Osteodonto-keratic Culture ­ Savannah hunting
Robert Ardrey 1961 Man the Mighty Hunter ­ African Genesis ­
Adult men hunting large game
Mikhail Nesturkh 1967 Herd instinct developed along with bipedalism as
our ancestors moved to more open territory.
Desmond Morris 1967 Mighty Hunter ­ The Naked Ape ­
Fur loss for easier sweating
Clifford Jolly 1970 The Seed Eaters ­ Savannah baboon model
John Napier 1971 Open grassy spaces provided Œarenas¹ where new
locomotor skills could be safely practiced.
Hatley & Kappelman 1980 Belowground food resources
Walker, Zimmerman & Leakey 1982 High dietary intake of carnivore livers
Scavenger model
Hanna & Brown 1983 Bouts of strenous activity for hunting or digging
outside the forest
Peter Wheeler 1984 Savannah foraging at noon, to minimise solar
radiation
David Carrier 1984 Dogged pursuit of swifter animals over 1 or 2 days
Sinclair, Leakey & Norton-Griffiths 1986 Bipedal trekking after herds of
migrating ungulates
Mark Skinner 1991 Savannah bee brood consumption ­
Tall grass savannah & tropical forest
Richard Wrangham et al. 1999 Cooking and bringing food to a processing
area
Bramble & Lieberman 2004 Endurance Running over vaste plains
Dennell & Roebroeks 2005 Ability to ingest large amounts of meat ­
ŒSavannahstan¹
Richard Wrangham 2005 Delta hypothesis ­ Okavango-like savannah ­
Omnivory

Whereas modern biology sees evolution as a sequence of overlapping niches
(Kemp 2007), the proposed Œopen plain¹ lifestyles of these early human
ancestors are discontinuous and have little or no overlap. Frequently they
are incompatible with each other. Moreover, they suppose that humans
collected foods without the typical adaptations that other mammals use when
they collect the same foods. We have no large digging-claws, for example, we
are slow runners (only some 36 km/hr over short, and some 20 km/hr over long
distances), and we are very prone to dehydration by depletion of water and
salts. We are heavily-built creatures with extensive fat tissues and (in
archaic Homo) heavy bones, features that are not seen in cursorial species.
Our cheekteeth lack the seed-grinding adaptations of baboons, while the
human gastro-intestinal tract and digestive anatomy and physiology resemble
frugi-omnivores such as suids, not carnivorous mammals (Stevens 1990). This
contradiction has been labelled the Œbaboon paradox¹, because we would
expect humans to be more similar to baboons if we evolved on the savannah as
they apparently did (Bender 1999).
The collection of waterside food resources, on the other hand, is compatible
with the presumed lifestyle of early apes, and fits with modern human
food-gathering strategies. Shifting from a fruit-based diet to a diet
including more waterside foods such as coconuts and shellfish does not
require significant behavioural modification. The use of tools to open
hard-shelled nuts and fruits is easily transferable so that the meat of
certain molluscs can also be procured (capuchin monkeys use tools to open
fruit, nuts and shellfish), and shellfish, like fruits and nuts, are sessile
food resources that need only be found and gathered, not chased or hunted.
From such fruit, shellfish, plant and egg-gathering it is not difficult to
envisage the incorporation of waterside catching of insects, frogs, fish or
birds, and the butchering of turtles, crabs, whale or bovid carcasses found
at the water¹s edge. We do not claim to know exactly how this waterside
lifestyle evolved, but we are confident that the limited diving skills of
humans came about as a result of increased time spent foraging under water.
As to how frequently our ancestors may have dived or waded or collected
fruit from trees or foods along the shore at low tide, or how long our
ancestors¹ waterside phase or phases may have lasted, these are all
questions requiring further investigation.

...

http://www.youtube.com/watch?v=i3mu6urkvjM

.

Relevant Pages

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    ... different ideas ­ some more improbable than others ­ were put forward to ... explain how savannah-dwelling ancestors might have found enough food and ... collection, liver consumption, or food collection at noon on open plains) ... Diverse savannah hypotheses of human origins. ...
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